Ink delivery systems generally deliver ink from a reservoir to ports on a print head. The ink travels through umbilicals or tubing, enters the printhead and then ends up on a printing substrate as selected by the delivery system within the print head. In hot melt ink printers, the ink takes the form of solid ‘sticks’ of ink that is then melted into a first reservoir. Depending upon the configuration of the printer, the ink may travel from the first reservoir to a smaller reservoir closer to the print head until print demand requires delivery of the ink to the print head.
Some current implementations of piezoelectric ink jet (PIJ) printers may use an ink delivery system to deliver ink to 16 ports on the print head asynchronously. These systems may contain 16 solenoid valves, air router manifolds, low and high pressure chambers, check valve disks, check ball assemblies and fluid routing plates. An air pulse drives the ink from the solenoid in a single plug flow, in some embodiments the flow was only 0.6 grams per sec. The introduction of the pressurized air pulses can cause foaming, overfill, and print head leakage or ‘drooling’ if more than 2 colors are simultaneously delivered to a single head.
Further, this implementation has limitations as to the maximum flow rate of the ink and the number of colors that can be delivered to the print heads simultaneously. The print head also has a higher than desirable impulse pressure and several parts, as listed above.